Yeah. In Oblivion I was on my way to city at the end of the main plot, and I let Jauffre fall behind. I then completely forgot about him and went about my business. Some time later I came back and found him lying dead on the ground, presumably killed by a random wolf/bandit/whatever.
I really felt bad about that :p
Also, I decided to 'try out' playing as a bad guy and killed the guy in the small village outside the city who claims to have treasure, felt really bad about that too :p
A game I'm developing with some friends:
www.xnagg.com/zombieasteroids/publish.htm
It is largely a technical exercise but feedback is appreciated.